1. Field of the Invention
The present invention relates to an image forming apparatus, and more particularly, to a paper cassette for an image forming apparatus.
2. Description of the Related Art
An image forming apparatus, which may be used in an office or a home, for outputting a desired image by fusing ink or toner onto paper, has a paper cassette for in seriatim supplying the paper sheets to a printing engine for printing.
FIG. 1 shows a conventional paper cassette 100 for a conventional image forming apparatus (not shown). As shown in FIG. 1, the paper cassette 100 is mountable in a body (not shown) of the image forming apparatus with a plurality of sheets of paper being stacked on a knock-up plate 110. The topmost sheet of the paper stacked on the knock-up plate 110 is in contact with a pick-up roller 10, and both corners of a leading edge of the topmost sheet are in contact with a paper separating finger 120.
As shown in FIG. 2, when the pick-up roller 10 is driven in a clockwise direction, force is exerted to the topmost sheet in the direction of A. In this condition, the leading end of the topmost sheet is hindered from advancing due to the presence of the separating finger 120 and thus a part of the leading end of the topmost sheet is curved away from the sheet underneath it, so that the paper is fed to a printing engine by a feeding roller (not shown).
This conventional arrangement is not without drawbacks. For example, if the distance between the pick-up roller 10 and the paper separating finger 120 is extended to accommodate the use of a large-sized paper, multiple sheets of paper may be picked up. Accordingly, in order to prevent the picking-up of multiple sheets of paper, the pick-up roller 10 has to be positioned within a predetermined distance from the paper separating finger 120.
However, it is impractical for the conventional paper cassette 100 of the conventional image forming apparatus to have the pick-up roller 10 which is always positioned at an optimal distance from the paper separating finger 120 because various-sized papers are used. And, when the paper in use is large-sized, the occurrence of multiple sheet pick-up increases.
It is known to employ two spaced pick up rollers to remedy this multiple sheet pickup problem for A4 size paper. When using two spaced apart pick up rollers, the distance between the two pick-up rollers can be extended in order to prevent the pick up of multiple sheets of A4 paper. In this case, however, there is a disadvantage in that paper of a narrow width such as A5 size paper cannot be used.